Ruthy

I just wanted to ask if it’s normal for a tire to need to be toped up with air every week?

I got a new tire (big apple) and a new inner tube, but have noticed that it needs topping up with air every week even though this bike might not even be used in that time. I thought could this be because the tire is Kevlar lined so it puts more pressure on the inner tube. Or is it just a faulty inner tube?

In contrast I have just a regular tire on the front which is run at the same PSI (60) and that virtually never needs inflating.

bradtx

Ruthy, Is the new inner tube black or orange? If orange (or possibly another color) it's probably a latex tube and they are more porus than a rubber tube. It's also possible that the tube has an issue with the valve or pinched during installation. The latter would usually cause a faster leak, so not very likely.

Brad

Ruthy

Hi Brad

The inner tube is black

10 Wheels

Completely Normal for me to Air Up my tires everyride and everyday if I am riding.

ben4345

I have to pump my tires every other day. Just the nature of the bicycle tires, especially road/training tires.

FBinNY 

Yes, having to top off tires is perfectly normal. The rate of air loss is related to the tube material and thickness, the ratio of volume to surface and the pressure. Weekly (or even more often) topping off of a road tire is par.

Narrow road tires lose air faster because they're narrow (volume/surface ratio) are ridden at high pressure, and tend to have thinner walled tubes. Mtn bike tires do better being wider, and generally running at lower pressure. Compare both to car tires with very high volume at low pressure, combined with much thicker walls. But even car tires lose air, they're just slower. Just about any inflated object loses air over time, including basketballs, balloons, you name it.

BTW- the tire material has nothing to do with it, just the tube.

curbtender

+1 The road tires don't seep any faster, they just don't hold the same volume of air. I top off my commuter every couple of days. usually around 5#.

Bill Kapaun

Om my Hybrid, I air up my 26C tires to 120 and in a day they are down to about 100.
My grocery getter's 26x1.25, I air to 100 and in 3-4 days they are down to about 90.
When it had 26x1.50 I'd air to 65-70 and a couple weeks they were around 50-55.

Altbark

Top up my tires every other day, five pounds or so. Al

FastJake

+1 has nothing to do with the tire. Tires (unless running tubeless) are not air tight and have no effect on the tube's ability to hold air.

Tire width and pressure are the determining factors in how fast they lose air. My road bike with 23mm tires at ~110psi needs air every other day, while my MTB commuter with 55mm tires at ~40psi can go a month or two without losing much air.

One thing that can matter is the size of the tube. If you have say 32mm tires and you stuff in a tube meant for 38mm tires it will stretch less and the rubber will be thicker, keeping the air in longer.

Ruthy

OK thanks for explaining that for me.

So I take it that there must be something wrong with the valve. As the tire in question has more volume and is run at the same PSI as the front tire which hardly ever needs air.

DannoXYZ 

Or you've got a pin-hole puncture that leaks slowly. Not unheard of for such low-pressure if you've got a 700x23c to 700x26c tyre. Snake-bite punctures are the most common result of low-pressure. If you've got 700x35-40c, then 60psi is more appropriate; depending upon weight and riding-style of course.

FBinNY 

It could be a leaky valve, or a pin hole in the tube, or a smaller tube stretched farther than the one in front, or a leak at the valve base flange, or nothing at all.

The valve is easiest to test and eliminate. Put a drop of spit on the top of the valve, or it you're more dainty than I am use a drop of soapy water. If it bubbles you have a leaky valve, if not you don't. leaky Schrader valves can be tightened with a valve core tool, which you can borrow from your favorite gas station or bike shop.

Testing for the other stuff means removing the tube, inflating it to twice it's normal size and submerging to locate the leak. Slow leaks are too small to be detected any other way. If you want to only confirm the existence of a leak, but not loacte it you can try to immerse the entire mounted tire one section at a time in a half full bath tub. You'll have to be very patient because your leak i so slow that it'll take a while to confirm a leak after it's settled.

In your shoes, I'd test the valve and if that's OK just live with it as.

fietsbob

Airpressure wants to equalize, in the tube and ouside world, a high pressure tube ,
thin, for it's lightweight,usual choice ,pumped up hard,
has even more force leaking thru the rubber's pores.

Thorn resistant HD tubes have thicker sides and even thicker bottom,
Increased amounts of rubber,
they will be needing less frequent inflation, but obviously be heavier ..

onespeedbiker

A little off topic, but when your looking for the puncture resistance from a Kevlar tire, some have a Kevlar layer or belt, but the vast majority have a Kevlar bead (aka aramid);as opposed to wire bead. So if you are looking for puncture resistance, make sure to buy the right tire.

DannoXYZ 

Yes, kevlar belt is what you want for puncture-resistance. I remember Specialized ads in the '80s for their kevlar-belted touring tyres with a speeding-bullet heading towards the tyre. I was interested in them due to getting 1-2 flats a week on my commute. I went from that to just 1 flat every two to three months. However, I discovered with some testing that they really aren't bulletproof though...

Ruthy

Well I tested the valve as kindly instructed and it’s not that.

So suppose it must be a slow puncture. It must have been a faulty inner tube, as both the tire and inner tube were new. Suppose it would be a hassle to take it back for an exchange at the bike shop. Trying to take anything back to small stores is like getting blood out of a stone. It’s at times like this I wish I had just gone to wallmat (controversial).

But thank you for your help.

ThermionicScott 

You can get punctures in new and perfectly good tires. It happens.

Al1943

Hopefully you have a good floor pump with a built in gauge, that's what you need.

Bill Kapaun

You could put a few inches of water in the bath tub and immerse the tire.
Rotate slowly & look for a small stream of bubbles.

DannoXYZ 

I've seen shop monkeys rush installs and resort to using tyre-levers or screwdrivers to pry the last bits of tyre on. This can pinch the tube and cause a small puncture and leak. As mentioned, the water-bucket test will tell you for sure. Even better is to remove the tube and pump it up so it's about the same diameter as it would be inside the tyre. Then roll it through the water-bucket one section at a time. The smallest of leaks will be apparent.

dbg

Or you could change it yourself. Fixing a flat (changing a tube --or even patching one) is a good skill to have when you are stranded on the road with a flat.

I would also point out that I put thicker tubes and slightly larger rims/tires on my kids' bikes (including their hipster single speeds) largely because they will seem to hold air for weeks / months. My 25C road bikes get air before every ride. My 26 inch commuter bike gets air once a month. My ancient Peugeot SS w/ 27" 1 1/4 Gatorskins get air every two weeks.

dbg

And don't go the department store route. They are much more likely to be sloppy than a real bike shop. Maybe you should try another bike shop --or have a discussion with the manager. Virtually every small bike shop I visit is very committed to customer service and PROPER bike maintenance. LBS rocks (pretty much).

Ruthy

I actually had the thought of just putting in some of the tire slime that we have for the car. Figured its easier than removing the tube.